Transistors called RCATs (Recessed Channel Array Transistors) are used as cell transistors in DRAMs. Those transistors have an advantage over conventional planar MOSFETs, being capable of reducing off-state current leakage. However, it is difficult to also satisfy the requirement for drive current with a RCAT structure, as in a MRAM.
In view of the above, S-Fin (Saddle-Fin) field effect transistors with greater channel widths W than those of RCATs have been suggested. However, the source portions of S-Fin transistors are not larger than those of RCATs. Therefore, it is difficult to achieve the required drive current with those S-Fin transistors.